This invention relates generally to remote measuring and more specifically to apparatus and a method for determining in a production lumber mill the straightness of cut of a saw with respect to a length of timber stock.
Because of the high cost of lumber materials and the awareness in current times of the extreme importance of conservation of natural resources, it has been observed that the straightness of cut of large production saws in lumber mills is a very significant factor in the amount of wasted wood in the output of large saw mills. That is, the more uneven or nonstraight the cut of material from the raw timber stock, the more additional wood must subsequently be removed from the lumber surfaces in order to cause those surfaces to be satisfactorily true for their intended purposes in the consumer market. For every tenth of a millimeter of increased straightness, it is estimated that thousands of board-feet are saved in the annual production of a large sawmill.
In order to set and maintain the sawing machinery in a manner to minimize the waste of material, it is essential that the straightness of cut be measured, then monitored and adjusted to achieve consistently maximum straightness for the cutting operation.
Previous known approaches to obtaining, in an economic and practical manner, measurements of straightness of cut to the necessary degree of precision are not satisfactory. The primary reason for this lack of satisfactory precision is that inherently a plurality of readings across the surface of the cut must be taken; and the fuzz and relative softness of the freshly cut surface material made it impossible to obtain "repeatability" of measurement within, at best, the order of a millimeter.
Accordingly, it is an object of the present invention to provide a lumber cutting measurement apparatus and method which is not subject to these and other limitations of the prior art.
It is another object to provide such apparatus with which a plurality of surface measurements may be taken with very high repeatability of reading.
It is another object to provide such apparatus in which the precision requiring steps in measuring are achieved by optical instruments mounted safely and remotely from the sawing operation.
It is another object to provide such apparatus and method which are simple, reliable, inexpensive, and operable by relatively unskilled operators.